Over the next few years the United Kingdom be be undergoing something of a cash
 revolution with its cotton paper bank notes being phased out and being replaced by cleaner, more secure, longer lasting and cheaper polymer bank notes.

The £5 polymer bank note is already here, but it will take untill 2020 for the £10 polymer and the £20 polymer to replace their cotton predecessors.

The current time line for the release and withdraw of bank note in England is as follows –

New Polymer £5 note issued on 13th September 2016
Old cotton £5 note withdrawn from circulation May 2017

New Polymer £10 note issued September 2017
Old cotton £10 note withdrawn from circulation 2018

New Polymer £20 note issued by 2020
Old cotton £20 note withdrawn from circulation by 2020